Enable both filters "URL to link" and "Media plugin" NONE of the filters must be set to Content and headings , only just Content Order the "URL to link" filter above the other one Go to your messages and create a new conversation with someone and send them a message In a separate browser (B) open that conversation and wait for new messages to come Send a few YouTube videos to that person E.g. https://www.youtube.com/watch?v=4_PsjQgkTM4 Confirm that the video loads in a player when: you sent the message you refresh the page you navigate away and back to this conversation the other sends you a message which is automatically pulled in (no refresh) the message is automatically pulled in B even though there weren't any video visible when the page loaded (because the conversation was almost empty) Access message/index.php?contactsfirst=1 directly The debug information at the bottom of the page must indicate "Pieces of content filtered: 0" Search for a contact which you've sent the video to Load the conversation and confirm that the video appears Test 2 Use Clean (simply because the layout does not cause a call to format_text) Download the attached file test.php to your dirroot . Go to your Admin > Plugins > Filters and ensure that none of the plugins are enabled on headings Multimedia should be enabled Access the file test.php Confirm that (using the data in and at the bottom of the page): The multimedia filter is enabled Pieces of content filtered is 0 Click "Click here!" and confirm that a video loads with a large play button Go to your Admin > Plugins > Filters and mark the multimedia plugin as "Off but available" Click "Click here!" again and confirm that the video does not load, only a link The page should not report the multimedia plugin as being enabled. Go to a course, and enable the "Multimedia filter" Note the course context ID (see bottom of the page) Access /test.php?contextid=YourCourseContextId Confirm that the page still shows Pieces of content filtered: 0 Click "Click here!" and confirm that a video loads with a large play button The page should report the multimedia plugin as enabled. Disable the filter in the course and confirm that the video will not load, only a link will be shown